Grilling on a deck is a wonderful way to bring your grill close to your house while making it easier to use with your barbeque, just being a few steps out on your deck. But wait! Did you spend thousands of dollars on beautiful composite decking? Can you use a gas grill on a composite deck?
Yes, Gas grills are safe to use on a composite deck. Composite decking is designed to a minimum of Class C fire rating similar to wood decking. Gas grills can be safely used on both composite and wood decking being raised high enough to provide enough clearance as not to damage either composite or wood decking.
As an extra layer of protection, people will often place a grill mat or pad to protect the decking from both heat and spills. A juicy patty dripping with all that goodness, can be dripping on your composite decking. A grill pat protects against drips and heat damage.
I have a fuller article about grill mats and best ones for composite decking
. Click the link to read more.
But composite decking does not need to be protected. It is safe to a gas grill on a composite deck. First, I am glad you are asking about a GAS grill. It is not recommended or safe to use a wood or charcoal grill on composite decking. Sparks and embers landing on the deck from the grill will damage or worst burn your deck. Gas grills are the safest to use, especially on a deck. With their control heat and bottom heat shields, minimizing heat transfer to the deck.
We are going to go over quickly 4 concerns about placing a gas grill on composite decking. Explaining why it is okay, along with a few short videos.
Will a gas grill melt composite decking?
The main
ingredient of composite decking is plastic. Plastic melts. I have played enough
with fire to know this. As a kid, I loved holding a piece of plastic over the
fire and watching as drops of plastic fell from the plastic I was holding in my
hand, splattering on the logs as the flames licked them up. Fascinating but not
your composite decking.
Yes, composite decking will become soft at a much lower temperature. It will vary by manufacturers, but Trex will soften at 176° Fahrenheit (80°C). I have moved 20’ (6m) long composite decking floppy as a wet noodle in the summer heat. The ends dragging in the ground with as the decking flopping up and down with every step. Heat does make composite soft.
But remember
that was a 20’ (6m) piece, a correctly built composite deck will have joist
every 16” (400mm) not 20’ (6m). Even with a slight deflection of the decking in
the heat, the spacing of the joist will still support the decking preventing
overt sagging or damage. The heat will soften the decking, but it will not
noticeably sag under the grill.
Also, your grill is designed to shield the material under it. We have all seen it at the popular campsite crowded with campers. The small portable gas grill is sitting on the wooden picnic table, searing hungry campers’ burgers. Yes, the smaller units produce less heat, but still, they are inches away from the wood table. As long as grease doesn’t drip on the table, it will not be damaged.
Before placing your gas grill on your composite deck, it is good to check the individual clearance required from composite. Melting occurs at a lower temperature, but maintaining the minimum heat clearance will help to protect your deck. Here is a quick chart of popular gas grills required clearances. They are for the sides and rear, but if the distance from the bottom is the same or higher than the rear required clearance, your composite decking should be safe. Heat rises.
| Barbeque Model | Rear Clearance | Side Clearance |
| Napoleon Rogue 500 | 20” (508mm) | 7” (178mm) |
| Napoleon Rogue 425 | 18” (460mm) | 7” (180 mm) |
| Weber-3600 | 18” (460mm) | 18” (460mm) |
| Weber E-310 | 24” (600mm) | 24” (600mm) |
| Regal™ 490 Pro | 30” (762mm) | 30” (762mm) |
| Monarch™ 390 | 30” (762mm) | 30” (762mm) |
| NexGrill 4-Burner | 24” (600mm) | 24” (600mm) |
| Kenmore Elite 600 Series Gas Grill | 24″ (600mm) | 24″ (600mm) |
An excellent personal check is, place your hand under the grill. If the decking is hot to the touch, turn the fire off, your grill is heating the decking to much. Often a gas grill will have a shelf, where the propane tank sits. Merely touching this shelf will tell you if it’s too hot, which is rare since that is where your flammable under pressure tank is. The gas grill is designed not to overheat below.
If you are curious about what it looks like when composite decking is melting, here is a video of hot charcoal being placed on composite decking. It is from 2013, and composite decking has undergone a lot of revisions since, but it’s a fun watch.
Will a gas grill start composite decking on fire?
Composite decking requires the same clearance as wood from a gas grill.
A previous investigation by R. E. Prince ( 7 ) demonstrated clearly that what he termed the “ignition temperature” for wood does not have a fixed value but is greatly influenced by the duration of exposure.
Forest Products Laboratory
Well, that isn’t helpful. Apparently, the fire ignition point is about drying and wood decking moisture levels varying from day to day and location. But for the sake of discussion, let’s go with paper, a wood product that has a more consistent ignition point. Wikipedia has a paper ignition point at 424-475°F (218-246°C). Yes, I understand that wood burns easier than wood decking but bear with me. If paper, a wood product will not ignite without a spark unless it is that hot.
Then at what temperature will a composite deck burn? It varies by manufacturer, but TimberTech decking is rated for 651°F (344°C) for flash ignition. The spontaneous ignition temperature of TimberTech composite decking has been tested at 788° (420°C). Those are temperature levels inside your grill, not below.
Trex goes one step further in their composite decking, manufacturing decking that is rated Class B or higher. With a slower rate of flames spreading then wood, Class C. Here is what Trex’s says about their composite decking.
“Nothing is more important than your safety outdoors. At Trex, we do everything we can to ensure it. Our Transcend and Select decking lines retain a Class B fire rating, while our Enhance decking lines retain a Class C fire rating; however, they are not fireproof. Moreover, our substructure product, Trex Elevations®, retains a class 1A fire rating.”
Trex
This is primarily
achieved by increasing levels of fire retardants in the composite decking. If
you are concern about your grill on your deck. It may be worth it to install
decking with a higher level of fire retardant. Do expect to pay a little more,
but still way cheaper than replacing your decking after a fire.
Gas grills and Composite Railing Clearance?
If your composite deck has composite railing, your gas grill will need clearance. Unlike aluminum railing, which requires little clearance form gas grills, composite railing does. Treat all-composite railing as combustible material and keep the minimum space between the grill and railing. Check your owner manual for required grill clearance or Google it. Better to be safe than sorry, always provide sufficient clearance and watch carefully for any impact from the heat of your grill.
As an added layer of protection, you can also protect your railing with a blanket. Click, to read the full article of about the type of blankets you should use to protect your deck railing.
If you would like to learn more about grill placement on a deck, click to read more about barbeque placement on deck in more significant details.
Will grease or food drippings stain composite decking?
Well, that depends. There are different levels of acidy in mustard and barbeque sauce. Don’t know about you but I grill, for I can lather my meat in sauce. The potential of dripping on the deck is high before going too far a little reminder from Mark Lotz about decking.
“treat like a kitchen floor.”
Mark Lotz
Regardless of the type of decking, all spills should be wiped up immediately. All decking chances of being stain increases with time. Remember the ten-second rule? If it is wiped up immediately, it’s still good, and your decking will be less likely to stain.
Most capped decking with its harder shell even after sitting awhile both ketchup and red wine can be wiped off without staining the decking. That harden cap not only protects the composite core from water but also minimizes stains. Yeah, for capping!
Matt Risinger has a great video in which he tests TimberTech composite and cedar decking against common barbeque staining, with a bonus scratch demonstration. It is here that he raises some concern about mustard residue on composite decking. It’s a very educational video if you wish to watch it.
Gas Grilling on a Composite Deck Conclusion
Yes, you can barbeque on a composite deck with a gas grill. The decking may soften with heat, but most gas grills are shielded enough not to impact the decking. The risk of fire and melting are low with a gas grill, but the use of a grill mat will help to protect your beautiful composite deck. The grill mat will also help to protect the decking from food stains. Enjoy your deck. Love your grill.
One last video of Trek decking with barbeque and chicken. It cleans off beautifully.